1. Field of the Invention
The present invention relates in general to a spray arm rotation device of an automatic tableware washer and, more particularly, to a structural improvement in such a spray arm rotation device for improving tableware washing effect by achieving reversible rotation of spray arm when spraying water upon tableware and washing the tableware.
2. Description of the Prior Art
With reference to FIG. 1, there is shown a spray arm of a tableware washer having a typical rotation device. In the drawing, the reference numeral 1 denotes a rotatable streamline spray arm that is a hollow symmetric body. A water inlet pipe 4 is coupled to the center of the bottom plate of the spray arm 1. The opposed side edges of the spray arm 1 are provided with side jet nozzles 3, which side jet nozzles 3 are diagonally opposed to each other and rotate the spray arm 1 about the pipe 4 by water jetting force as will be described herein later. The spray arm 1 is also provided with a plurality of top spray nozzles 2 on its top plate.
In operation of the above spray arm, the water is supplied to the interior of the hollow spray arm 1 through the water inlet pipe 4. The water in turn is primarily jetted from the side nozzles 3 at a water jetting velocity.
When the water is jetted from the side nozzles 3 as described above, the water jetting forces generated at the nozzles 3 cause the spray arm 1 to be rotated counterclockwise about the water inlet pipe 4 in a direction opposed to the water jetting direction of the jet nozzles 3 as shown at the arrow of FIG. 1 due to the third law of motion. As a result of rotation of the spray arm 1, the top spray nozzles 2 of the spray arm 1 spray the water upon the tableware while varying their spraying angles, thus to wash the tableware.
However, the above rotation device for spray arm 1 has a problem as follows. That is, the side jet nozzles 3 of the rotation device are fixed to the opposed edges of the spray arm 1 and always jet the water in predetermined directions, so that the rotation device can not help rotating the spray arm 1 in a predetermined direction opposed to the water jetting direction of the side jet nozzles 3. In this regard, the water spraying directions of the top spray nozzles 2 of the spray arm 1 are fixed, so that the top spray nozzles 2 fail in uniform and effective washing of the tableware.
If described in detail the operation of the spray arm 1 having the above rotation device, the water spraying direction of the top spray nozzles 2 is perpendicular to the rotating direction of the spray arm 1. Therefore, trace of the sprayed water of the top spray nozzles 2 of the spray arm 1 becomes the tangent line of the rotating direction of the spray arm 1 as shown in FIG. 2A.
As described above, the trace of the sprayed water of the top spray nozzles 2 of the spray arm 1 is set by the rotating direction of the spray arm 1, so that the trace of the sprayed water of the top spray nozzles 2 is inevitably fixed when the rotating direction of the spray arm 1 is fixed.
For example, when letting bowls be placed in the tableware washer as shown in FIGS. 2B and 2C and letting the spray arm 1 be rotated so as to form water spraying direction as shown in FIG. 2B, the sprayed water successfully washes the outside surfaces of the bowls but fails in successful washing of the inside surfaces of bowls. On the contrary, when letting the bowls be placed in the tableware washer as shown in FIGS. 2B and 2C and letting the spray arm 1 be rotated so as to form water spraying direction as shown in FIG. 2C, the sprayed water successfully washes the inside surfaces of the bowls but fails in successful washing of the outside surfaces of bowls.
As described above, the typical rotation device for spray arm of tableware washer has the problem that the rotation device can not help rotating the spray arm in a predetermined fixed direction, so that the spray arm fails in successful washing of the tableware regardless of rotating direction of the spray arm.